The WG2229100039 piston is engineered from high-grade, wear-resistant materials designed to endure millions of shift cycles. In a pneumatic system, the integrity of the piston and its seals is paramount; even a minor air leak or a slightly deformed piston can lead to sluggish range transitions or a complete failure to engage high or low gears. By choosing this genuine OEM part, you are ensuring that your transmission maintains its factory-spec response time and reliability. Don’t let a failing auxiliary box component compromise your truck’s performance—invest in authentic Sinotruk spare parts to keep your fleet moving efficiently.

Technical Specifications

This range shift piston is specifically designed for the HW series transmissions that power the global fleet of SINOTRUK HOWO and A7 trucks.

Specification	Value
Part Number	WG2229100039
Alternative Names	Range Stop Piston, Range Gear Piston
Product Name	Gearbox Range Shift Cylinder Piston
Application	SINOTRUK HOWO, HOWO A7, SITRAK, and other trucks with HW series gearboxes (e.g., HW19710, HW19712)
Brand	SINOTRUK (Original OEM)
System Type	Pneumatic Range Shifting (Auxiliary Box)
Material	High-Strength Aluminum Alloy / Steel Composite
Function	Actuates the range shift fork for high/low gear transitions
Compatible Seals	Requires standard range piston O-rings (sold separately)
Condition	Brand New

Installation Notes

Replacing the range shift cylinder piston is a technical task that involves working with the transmission’s pneumatic system. It is highly recommended that this work be carried out by a qualified heavy-duty mechanic.

1.System Depressurization: Before starting, ensure the vehicle’s air system is completely drained. Working on a pressurized pneumatic system is dangerous and can cause injury or damage to the transmission components.

2.Accessing the Cylinder: The range shift cylinder is located at the rear of the transmission housing, near the auxiliary box. You will need to remove the cylinder cover to access the WG2229100039 piston.

3.Inspection and Cleaning: Once the old piston is removed, thoroughly clean the internal walls of the cylinder. Inspect the cylinder bore for any scoring or signs of wear. A damaged cylinder wall will quickly ruin a new piston and its seals.

4.Seal Preparation: Always use new O-rings when installing the new piston. Apply a light coating of high-quality pneumatic grease or clean transmission oil to the seals and the piston body to ensure smooth initial movement and a perfect air seal.

5.Installation: Carefully slide the new piston into the cylinder, ensuring the seals are not pinched or twisted during insertion. Reinstall the cylinder cover using a new gasket (such as the WG2229100189 paper pad) to prevent air leaks.

6.Testing: Re-pressurize the air system and test the range shift function multiple times while the vehicle is stationary. Listen for any air leaks and ensure the transition between high and low ranges is crisp and immediate.